I can look back over quite a long period of racing at a reasonable level. When I started, brakes were frankly awful - anyone recall Universal side pulls, Weinmann, Mafac centre pulls (one finger enough - my backside!). Gradually brakes improved until the very efficient dual pivot jobs appeared. Powerful enough to lock up IN THE DRY. This is where we are today, carbon rims have metal facings or use special pads, and they will wear out eventually under constant heavy use.
Discs get hotter and will wear out too.
So, what is the purpose of disc brakes. Well, they are claimed to be even more powerful and this shows in cross and mtb, where people can lock up and slide through corners a bit faster than with mud clogged rim brakes. So that's an advantage.
Whether disc brakes offer an advantage on the road when the limiting factor is grip is another matter.
There is one clear advantage, the manufacturers get to sell a completely new load of frames and wheels, and make more money.
Eventually for safety, if discs come into local level road racing, the rules will have to insist on everyone using them. Mixed peloton = unsafe. Comparing to cross and mtb is daft, they don't have 60-200 people close packed for hours at a time at 40 - 65 kph.
More money for manufacturers as everyone has to re-equip for the start date. Good thing? Loads of perfectly good non-legal road bikes for sale at good prices because they are useless for competition.
So, who benefits? Riders, not really as they all have perfectly good brakes already on bikes which cost loads. So they lose out. Organisers and officials, have to sort out loads of hassle as the change happens, not much fun. Suppliers, do very nicely thank you.
Who is driving the change? The Sporting Goods Manufacturers Association who seem to be pushing UCI as hard as they can to get it through because they know that if the pros go disc eventually everyone else will follow.
How strange - not.
